Communication systems allow the user of a terminal or device, such as a personal computer or mobile phone, to communicate with other users across a computer network such as the Internet. Communication systems, such as packet-based communication systems (including video over Internet protocol (IP) communication systems), allow users to exchange live video streams over the Internet, thereby facilitating video calls to be made over the communication system. Packet-based communication systems may be beneficial to the user as they are often of significantly lower cost than communication systems using fixed line or mobile networks. This may particularly be the case for long-distance communication. To use a video-over-IP system for video calling, the user installs and executes client software on their terminal. The client software provides the video IP connections as well as other functions such as registration and authentication. In addition to video communication, the client may also provide further features such as audio, instant messaging (“IM”), SMS messaging, and voicemail.
To engage in a video call a user has a camera, such as a webcam, which is used to capture video data of the user. The captured video data is transmitted to the far end terminal of the video call over the communication system, where it can be output in real-time to thereby display the video data to a user of the far end terminal in the video call. Similarly, video data of the user of the far end terminal may be captured and transmitted to the near end device over the communication system for output to the user of the near end terminal in real-time in the video call. As well as transmitting the video data between the users in the video call, audio data may be received (e.g. using microphones) and transmitted between the users of the video call, thereby allowing the users to communicate with each other both visually and aurally in the video call. The output of video data in a video call can enhance a user's experience of the call as it allows the user to perceive visual data, in combination with audio data received from the other user in the call.